# Relationship history for MSHA mine 3602257

Current hierarchy: **Zigarski Albert → Keno Coal Company → No 1 Slope**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Keno Coal Company Inc → No 1 Slope; 1950-01-01 to 1983-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Dunsavage Raymond Et Al → No 1 Slope; 1950-01-01 to 1983-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Dunsavage Raymond Et Al → Keno Coal Company Inc; 1950-01-01 to 1983-11-13; source msha-controller-operator-history
- **operator_operates_mine:** Keno Coal Company → No 1 Slope; 1983-11-14 to 1984-11-25; source msha-controller-operator-history
- **controller_controls_mine:** Harner Roy E & Delbert L Artz → No 1 Slope; 1983-11-14 to 1984-11-25; source msha-controller-operator-history
- **controller_controls_operator:** Harner Roy E & Delbert L Artz → Keno Coal Company; 1983-11-14 to 1984-11-25; source msha-controller-operator-history
- **operator_operates_mine:** Keno Coal Company → No 1 Slope; 1984-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Zigarski Albert Et Al → No 1 Slope; 1984-11-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zigarski Albert Et Al → Keno Coal Company; 1984-11-26 to current/open; source msha-controller-operator-history